Could someone please advise on the correct footwork (heel-toe) in a double Lockstep in International Style Tango. My question is whether the lady, going forward, should take a heelstep on every step.

The Lockstep is preceded by Back Rock after Open Promenade with the Man going backwards, the Lady left forward, right crosses behind left, left forward, right crosses behind left, left forward, (then follows right to side, left closes to right.) The timing is quick-and-quick-and-quick- (side-close).